The RMT union's complaints relate to the transfer of Piccadilly Line control-room services to a new centre in Hammersmith.
Transport for London plans to replace a number of separate control centres with a single one from 2017.
The Rail, Maritime and Transport Union says the move will cause job losses - and that there are also issues with rates of pay and the lack of "any meaningful offer for Service Control staff for the Olympic period."
More top news
14-year-old Joshua Mould has learning difficulties and struggles to communicate.
David Haines' daughter tells ITV News families of IS victims will not get closure until there is a "bullet between the eyes" of Jihadi John.
The Essex boy will be racing for a new team - Manor - after the team formerly known as Marussia came out of administration.